The manufacture of absorbent articles such as diapers, training pants, incontinence underwear articles, and the like, typically includes compiling and processing a web substrate as a continuous band of end-to-end or side-to-side work pieces from which respective absorbent articles are eventually derived, typically one absorbent article from each work piece. The compiling and processing includes assembling various elements to the web substrate, and shaping and configuring the thus assembled composite web substrate.
Upon completion of the various manufacturing steps, the web is severed across a transverse dimension of the web, typically across the full width of the web, to thereby separate from the web respective ones of the work pieces as separate and distinct units of absorbent article product.
During the fabrication process, the work pieces are typically only partially defined in the web until such time as the work pieces are severed from the web as units of product. In the web, the work pieces are generally associated with respective repeat elements on the web and the number and positioning of the respective elements in the finished units of product.
Thus, one familiar with the definition of the products to be derived from the web can, by observing the locations and repeat frequencies of respective elements on or in the web, typically perceive the number and locations of respective ones of the work pieces on the web, and can correspondingly perceive the number and locations of the respective units of product which will be derived from the web.
In manufacturing certain absorbent articles, trim material pieces are defined in trim areas; and the trim material pieces are severed and removed from the web. Exemplary of such trim areas, and trim pieces cut therefrom, are cut-outs associated with leg openings such as in, for example, diapers, training pants, incontinence underwear articles, and the like.
Various elements are positioned on the web at specific locations for each unit of product, consistent with the relationships desired between the respective elements in the finished unit of product. So long as an element to be placed on the web has sufficient acuity and measurable intensity of image, and suitable outline, to be readily discerned by a registration sensor, the element can be properly placed and its placement checked by a relatively inexpensive e.g. optical sensor, or other sensing device.
Where the properties of the element do not have sufficient acuity and measurable intensity of image, and suitable outline, to be readily discerned by a registration sensor, controlling placement of the element, and confirming proper placement, is more difficult and thus requires more costly sensing apparatus. Controlling placement becomes even more difficult where two different elements are to be registered with respect to each other and neither of the elements has sufficient acuity and measurable intensity of image, and suitable outline, to be readily discerned by a registration sensor.
In most cases of registering two elements to each other, it will suffice for one of the elements to have sufficient acuity and measurable intensity of image, and suitable outline, to be readily discerned by a registration sensor. The sufficient element then becomes the reference to which the second element is registered.
But where neither element satisfies the sufficiency of definition requirement, achieving registration requires a different solution. In such case it is common to print registration images periodically along the length of the web, for the sole purpose of providing reference marks against which other elements can be registered. Such reference marks may be printed on the web in an area where they will be inconspicuous in the finished product. In some cases, the web is intentionally made sufficiently wide to provide for an edge trim extending unbroken along the full length of the web, wherein the purpose of the edge trim is to provide a printing locus for printing the registration marks and then removing the registration marks by cutting away a constant-width edge trim, including the registration marks.
But such procedures are expensive in terms of wasted raw material. In addition, such procedures are create excessive manufacturing waste which must be either recycled, or sent to landfill, both of which options add cost to the product.
It is an object of the invention to provide a process of fabricating units of product from a web, including defining and developing first and second features of a web by a novel set of steps.
It is a specific object of the invention to use optionally temporary registration images as intermediaries, registering cut-outs and other web features to each other while neither of the elements being registered has sufficient acuity and measurable intensity of image to serve as a registration mark.
It is another object to register, along a first length of the web, a first set of other web features and boundaries of a first set of trim areas, wherein neither the trim areas nor the other web features can be reliably used as a registration reference.
It is a further object to register along a second length of the web, a second set of trim areas and a second set of other web features, different from the first set of other web features and wherein neither the trim areas or the second set of other web features can be reliably used as a registration reference, the trim areas and other web features being registered using intermediary registration reference marks.
It is another object of the invention to provide such intermediary registration reference marks as temporary marks, removed from the work pieces along with routine removal of trim areas from the web.
It is yet another object to force registration of printed indicia with the registration reference marks by applying the printed indicia using the same application device which prints or otherwise applies the registration image.
It is a more specific object to provide such registration of first and second elements neither of which is reliable for use as a registration reference mark while producing units of product devoid of such reliable registration marks.
A first family of embodiments of the invention comprehends, in the process of fabricating units of personal care absorbent article product by assembling a composite product web and then severing units of absorbent article product from the web, a method of registering a periodic repeat element of the web to a periodic master reference element of the web, wherein the periodic repeat element is insufficiently distinctive for reliable registration to another element of the web by detection. The method comprises assembling together a plurality of web elements, thereby progressively defining the composite product web, and units of product in the web including, (i) using an application device, applying marking material defining a set of registration images periodically along a length of web, on trim areas defining trim material pieces removed from the web in defining the units of product, and (ii) applying the periodic repeat elements periodically along the length of the web, using the application device to force registration of the periodic repeat elements to respective ones of the registration images during such application. A sensor is used to sense ones of the registration images and, based on such sensing, the method registers ones of the periodic repeat elements to corresponding ones of the master reference elements, respective ones of the registration images thus being used as registration intermediaries to establish relative locations of the periodic repeat elements to the respective periodic master reference elements. After registering a respective periodic repeat element to a respective master reference element, the method further contemplates removing from the web the trim material piece corresponding to the respective registration element, thereby also removing the respective registration image from the web.
The method can include confining the registration images to the trim areas, whereby the removing of the trim material pieces also removes the entireties of the registration images.
In some embodiments, respective ones of the registration images also act as indicators indicating presence or absence of respective trim material pieces after the removing step.
The method can include sensing for a respective registration image after removing the respective trim material piece.
In preferred embodiments, the registration images have sufficient size, configuration, and contrast to background, consistent with sufficient acuity and measurable intensity of image, and suitable outline, to be readily detected by a low resolution sensor, whereby the registration images serve as low cost registration reference marks for determining positions of respective elements along the length of the web.
Some embodiments of the invention include, using a suitable such sensor, and suitable corresponding such marking material, sensing the marking material independently of visible light from the respective registration image.
Some embodiments include sensing the registration images at the trim areas utilizing magnetic flux.
Some embodiments include sensing the registration images at the trim areas utilizing energy in one or both of the ultraviolet spectrum and the infrared spectrum.
In some embodiments, the combination of the registration images, the sensor, and a controller operating in control of a respective product fabrication line, having capacity to discern up to about 1000, optionally no more than 500, further optionally no more than 200, also optionally no more than 50, yet further optionally no more than 20, of the registration images per minute along a length of the web.
In some embodiments, the invention contemplates using a dark ink, sufficiently dark that the ratio of opacity of the reference marks to opacity of a background around the reference marks is no more than about 0.67/1, and including detecting the registration images utilizing an optical sensor.
Preferred embodiments include creating the registration images using magnetic ink, passing the registration images through a magnetic field, to magnetize the registration images, and passing the magnetized registration images through a such sensor responsive to magnetic flux.
Some embodiments include generating heat selectively in the registration images, and sensing the heat using an infrared such sensor.
In some embodiments, the method includes applying a first set of the periodic repeat elements along a first length of the web, using the registration images as reference marks for determining the respective relative locations of the first set of the periodic repeat elements with respect to respective ones of the master reference elements, and applying a second set of the periodic repeat elements along a second length of the web, using the registration images as reference marks for determining the respective relative locations of the second set of periodic repeat elements.
Some embodiments include defining respective ones of the trim areas to extend about at least two separate and distinct ones of the registration images.
Preferred embodiments include, after removing a respective trim material piece, sensing for marking material on the respective work piece, optionally through a visually obstructive layer between the sensor and a respective registration image, to determine whether the marking material was successfully removed.
In preferred methods, each work piece comprises at least a respective one of the registration reference marks or registration images.
In preferred embodiments, each unit of product so severed from the web is devoid of the registration reference marks or registration images.
In preferred embodiments, the periodic repeat elements comprise printed images periodically repeated along the length of the web, whereby the printed images are in registration with respective ones of the master reference elements.
A second family of embodiments contemplates a method of processing sequential first and second different lengths of web in fabricating respective first and second different products, the products differing from each other according to respective first and second different sets of repeat elements on respective first and second leading and trailing such lengths of the web. The method comprises processing the first length of web on a line of processing machines and controls therefore, and making first units of product therefrom, including (i) processing a first such length of web bearing first periodic repeat elements registered to marking material defining periodic first registration images, and wherein the first periodic repeat elements are not readily sensed for reliable registration to another element of the first length of web, and (ii) using a sensor, sensing ones of the first registration images, and based on such sensing, registering the respective first registration images to corresponding first periodic master reference elements and thereby using the first registration images as intermediaries for indirectly registering a multiplicity of the first periodic repeat elements to respective ones of the first periodic master reference elements in fabricating an at least temporarily ongoing stream of units of product from the first length of web.
The method further includes, subsequent to processing the first length of web, processing the second length of web on the line of processing machines and controls therefor, and making second units of product therefrom, without modifying the processing operation to accommodate the differences between the first and second sets of repeat elements, including processing the second such length of web bearing the second periodic repeat elements registered to marking material defining periodic second registration images, the second registration images having a sensing characteristic in common with a respective sensing characteristic of the first registration images, and wherein the second periodic repeat elements are not readily sensed for reliable registration to another element of the second length of web, and using the sensor, sensing ones of the second registration images, and based on such sensing, registering the respective second registration images to corresponding second periodic master reference elements and thereby using the second registration images as intermediaries for indirectly registering a multiplicity of the second periodic repeat elements to respective ones of the second periodic master reference elements in fabricating an at least temporarily ongoing stream of units of product from the second length of web. The sensing characteristic common to the first and second registration images provides a common link to the processing machines and controls therefore, enabling processing of the second length of web with suitable registration of the second periodic repeat elements to the second periodic master reference elements without adjusting the line of assembly machines to account for the differences between the first and second sets of repeat elements.
In preferred embodiments, the first and second sets of products comprise absorbent personal care articles, each such absorbent personal care article having a front portion, a rear portion, and a crotch portion between the front and rear portions, and leg cut-outs on opposing sides of the respective absorbent personal care article in the crotch portion, created by severing and removing trim material pieces defined at trim areas on opposing sides of the web.
In some embodiments, the method contemplates defining one of the trim areas about each of the registration images such that respective ones of the registration images are removed when the respective trim material pieces are removed.
In preferred embodiments, the registration images have leading edges, oriented transverse to a direction of movement of the web, sufficiently sharply-defined as to be readily discerned by a such sensor having relatively low sensitivity and relatively low resolution capabilities, with sufficient resolution that the registration images can serve as registration reference marks under conditions of relatively low sensor sensitivity and relatively low resolution.
In preferred embodiments, the method includes (i) sensing timing of a respective registration image moving past a fixedly mounted such sensor, (ii) based on the timing of the registration image moving past the sensor, defining a location of a respective trim area associated with the respective registration image, (iii) removing the trim material associated with the respective trim area, and (iv) subsequently performing a sensing step sensing for marking material to determine success or failure of removal of such marking material and thus success or failure of removal of the trim material associated with the respective trim area.
Further to preferred embodiments, each unit of product, prior to removing the trim material pieces, comprehends the registration images and one or more elements of one of the first and second periodic repeat elements, and after removing the trim material, comprehends the one or more elements of one of the first and second periodic repeat elements and at least one of the cut-outs.
In a third family of embodiments, the invention contemplates, in the process of fabricating units of personal care absorbent article products by assembling a composite product web and then severing units of absorbent article product from the web, a method of providing indexed periodic repeat elements on the web, and correspondingly on the resultant personal care absorbent article products, wherein at least some of the periodic repeat elements are insufficiently distinctive for reliable registration to another element of the web by detection. The method comprises assembling together a plurality of web elements, thereby progressively defining the composite product web, and units of product in the web including, (i) using an application device, applying marking material defining a set of registration images periodically along a length of the web, (ii) applying the periodic repeat elements periodically along the length of the web, using the application device to force registration of the periodic repeat elements to respective ones of the registration images during such application, and (iii) repeatedly indexing the periodic repeat elements through a defined set of less than 1000 different images.
The method further includes using a sensor, sensing ones of the registration images and, based on such sensing, registering at least some of such insufficiently distinctive, indexed ones of the periodic repeat elements to corresponding ones of the master reference elements, respective ones of the registration images thus being used as registration intermediaries to establish relative locations of the periodic repeat elements to the respective periodic master reference elements.
The method can include, after registering a respective indexed periodic repeat elements to respective master reference elements, removing from the web the trim material pieces corresponding to the respective registration elements, thereby developing corresponding cut-outs and removing the respective registration images.
In some embodiments, such personal care absorbent articles have ones of the cut-outs on opposing sides thereof, respective ones of the cut-outs being derived from opposing sides of the web.
In preferred embodiments, the registration images also act as indicators indicating presence or absence of the trim material pieces after the removing step.